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A first-of-its-kind energy-storage system has been added to the grid in the UK. The 5MW/15MWh system stores energy in an unusual way: it uses excess electricity to cool ambient air down to -196°C (-320°F), where the gases in the air become liquid. That liquid is stored in an insulated, low-pressure container.

When there's a need for more electricity on the grid, the liquid is pumped back to high pressure where it becomes gaseous again and warmed up via a heat exchanger. The hot gas can then be used to drive a turbine and produce electricity.

Further Reading

The system is called Liquid Air Energy Storage (LAES, for short), and if you're thinking it sounds remarkably like Compressed Air Energy Storage (CAES), you're right. LAES takes filtered ambient air and stores it so it can be used to create electricity later, just like CAES. But LAES liquifies the air rather than compressing it, which creates an advantage in storage. Compressed-air storage usually requires a massive underground cavern, but LAES just needs some low-pressure storage tanks, so it's more adaptable to areas that don't have the right geology.

In case "liquid air" is stretching your imagination, check out this video to see how it's done.

LAES has also been compared to pumped hydro, where excess electricity is used to pump water up to a reservoir above a hydroelectric turbine. Pumped hydro and LAES both can be designed to provide power for hundreds of thousands of homes. But unlike pumped hydro, LAES doesn't require a water system or elevation differences to operate.

On the other hand, an LAES system is only 60- to 75-percent efficient, compared to the 75- to 85-percent efficiency of lithium-ion batteries. Lithium-ion batteries can also respond to minute frequency changes on the grid almost instantaneously, whereas LAES systems deliver electricity by turbine, so their delivery response time isn't as quick.

OK, what about this particular plant?

A view of Pilsworth from a distance.

Highview Power

The smaller pilot plant that Highview built in 2011 ran until 2014. Now the system is being studied at a university.

Highview Power

This new LAES system is being built by a company called Highview Power in Bury, near Manchester, UK, and it's connected to the Pilsworth Landfill gas site, a power plant that burns methane from the landfill to create electricity. The plant was built in partnership with Viridor, a recycling and renewable energy company, and IT received £8 million from the UK government (about US$10.7 million).

This demonstration liquid-air storage system was preceded by a 350kW/2.5MWh pilot system at an 80MW biomass plant west of London between 2011 and 2014. The Bury demonstration plant is, in fact, significantly behind schedule—it was commissioned in 2015 and was expected to be up and running shortly thereafter.

Further Reading

The power stored at Pilsworth will be aggregated by a company called KiWi Power, which will manage when the LAES system will charge and discharge. A press release noted that this 15MWh system will be able "to power about 5,000 average-sized homes for around three hours." Generally, storage systems have found a niche on the power grid by providing short-term and ancillary services, but long-duration options will be needed as more and more intermittent renewables are added to the grid.

The same press release makes the case for LAES as perhaps even more environmentally friendly than batteries. "No exotic metals or harmful chemicals are involved, and the process does not release any carbon emissions," Richard Pennells, managing director of energy at Viridor, stated. "The plant comprises mostly of steel, which has a lifespan of between 30 to 40 years, in comparison with 10 years for batteries. At the end of life, a LAES plant can be decommissioned and the steel recycled."

Highview Power's Pilsworth plant is designed to capitalize on opportunities for heat efficiency, too. It uses heat from the gas plant it's connected to in the re-heating process, and the company has also reportedly developed a proprietary system to store the "waste cold" that is created when air is discharged (PDF). The cold is used to increase the efficiency of the process that converts air into liquid.

Highview says capturing "waste cold" can also occur during the regasification of Liquified Natural Gas (LNG). LNG has to be stored at very cold temperatures, and if that cold can be harvested and used to make a Liquid Air Energy Storage system more efficient, that would make the battery more competitive.

The company has also explicitly said that it will test its system at Pilsworth for use in US regional markets.

Since this is the first such commercial LAES system, there's obviously a lot to be learned, and there's no reason to think this technology will conquer the utility-scale battery storage market any time soon. But it is a cool new option to have in a renewable-focused future.

The first part I see as a plus given the materials that go into lithium batteries....but yeah....I don't think ANY of the grid storage systems generate further carbon emissions....that just doesn't make sense.

When there's a need for more electricity on the grid, the liquid is pumped back to high pressure where it becomes gaseous again and warmed up via a heat exchanger. The hot gas can then be used to drive a turbine and produce electricity.

Pressurizing the liquids doesn't turn them into gas. It's the heating that does that. However, just like in a gas turbine engine, it's thermodynamically beneficial to add energy at the highest pressure so that's why they pressurize then heat rather than vice versa.

Slight side-track. I visited a friend's off-grid cabin recently. She was very proud to show me her "invention." She uses solar panels for generation and rather than battery storage had the idea to use the excess energy to pump water into a tower. The water in the tower would be released and flow through a small hydro-turbine to generate electricity during times of low-solar/night.

She was very proud and has big thoughts in her head about selling the concept. I didn't have the heart to tell her. I did, however, forward a copy of this article to her this morning.

Well it's not 100 percent efficient, so the 25-40 percent energy wastage could be regarded as contributing carbon emissions. But better some surplus energy saved than none. Also the plant lifetime quoted is a bit misleading as the expensive pumps and turbines will wear out faster than the steel tubing .

The main problem is that Great Britain has an instantaneous energy demand of 35 - 50 GWSee it in real timeso it will take a lot of this sort of storage to make up for days when the wind doesn't blow and the sun doesn't shine. They need to be storing Gigawatts rather than Megawatts and I look forward to seeing this technology scaled up, or one of this size added to every wind farm.

Slight side-track. I visited a friend's off-grid cabin recently. She was very proud to show me her "invention." She uses solar panels for generation and rather than battery storage had the idea to use the excess energy to pump water into a tower. The water in the tower would be released and flow through a small hydro-turbine to generate electricity during times of low-solar/night.

She was very proud and has big thoughts in her head about selling the concept. I didn't have the heart to tell her. I did, however, forward a copy of this article to her this morning.

I fear she'll be crushed.

I'm not sure why she'd be crushed. This is a completely different storage technology. What she's got is a small-scale pumped hydro system. If she could develop a turnkey off-the-shelf system there's no reason why it couldn't potentially be economically viable (for a relatively niche market, probably). It's not a new technology but at the scale she's talking I don't think it's a market that's been adequately exploited.

So it's got worse round trip efficiency than CAES, will have massively higher operating cost than CAES, but has a slight advantage in footprint and site selection. That doesn't seem like that compelling of an argument given how efficient distribution grids are. Put the CAES system wherever it can be sited and you'll still have very significantly higher efficiency and won't have to maintain a complex cryo system. I mean if we run out of sites for CAES systems sure, it's worth trying but we're so far from that eventuality that I can't see where this is advantageous to be doing now unless you're looking to export it to places like Hawaii where CAES will be hard or impossible to site.

Slight side-track. I visited a friend's off-grid cabin recently. She was very proud to show me her "invention." She uses solar panels for generation and rather than battery storage had the idea to use the excess energy to pump water into a tower. The water in the tower would be released and flow through a small hydro-turbine to generate electricity during times of low-solar/night.

She was very proud and has big thoughts in her head about selling the concept. I didn't have the heart to tell her. I did, however, forward a copy of this article to her this morning.

I fear she'll be crushed.

I'm not sure why she'd be crushed. This is a completely different storage technology. What she's got is a small-scale pumped hydro system. If she could develop a turnkey off-the-shelf system there's no reason why it couldn't potentially be economically viable (for a relatively niche market, probably). It's not a new technology but at the scale she's talking I don't think it's a market that's been adequately exploited.

Great minds think alike? There's room at the small homesteader end of the market although DIY will probably be more popular.

I wonder how many heat exchangers the LEAS plant has. It has to heat up the cold air and cool down the warm used air.

So it's got worse round trip efficiency than CAES, will have massively higher operating cost than CAES, but has a slight advantage in footprint and site selection. That doesn't seem like that compelling of an argument given how efficient distribution grids are. Put the CAES system wherever it can be sited and you'll still have very significantly higher efficiency and won't have to maintain a complex cryo system. I mean if we run out of sites for CAES systems sure, it's worth trying but we're so far from that eventuality that I can't see where this is advantageous to be doing now unless you're looking to export it to places like Hawaii where CAES will be hard or impossible to site.

I think you answered your own question. CAES requires very specific conditions to be considered for installation, while this technology can be plonked down more-or-less anywhere. Its not an either-or, it's expanding options for energy managers. It remains to be seen whether it will be economically viable, and competitive with other storage options (and under what conditions).

I've got serious doubts. Hasn't the problem with the compressed-gas storage always been the efficiency loss due to compression heating? This has that turned up to 11.

If it works it works, and I'm happy to have it. But the proof will be in the prices.

The thing is, you're cooling the air to liquefy it. Pressure doesn't* enter into it until a later stage (you heat the liquid air up again in a smaller volume, thereby creating high pressures to use the air as working fluid). Thus, no compression heat, which is indeed a major drawback of CAES systems.

I've got serious doubts. Hasn't the problem with the compressed-gas storage always been the efficiency loss due to compression heating? This has that turned up to 11.

If it works it works, and I'm happy to have it. But the proof will be in the prices.

It really seems from the pdf like they're focusing on it as a consumer of waste-cold, or waste-heat. Since the plant size is so much smaller than CAES it can be more easily co-located in places where there's significant amounts of one or both resources available.

It doesn't seem like it's going to be economic as a stand-alone plant.

I've got serious doubts. Hasn't the problem with the compressed-gas storage always been the efficiency loss due to compression heating? This has that turned up to 11.

If it works it works, and I'm happy to have it. But the proof will be in the prices.

The thing is, you're cooling the air to liquefy it. Pressure doesn't* enter into it until a later stage (you heat the liquid air up again in a smaller volume, thereby creating high pressures to use the air as working fluid). Thus, no compression heat, which is indeed a major drawback of CAES systems.

* Of course, pressure is always a factor when dealing with fluids.

There actually is compression heat, presumably from the compressors in the refrigeration cycle - and they do/could capture it:

If there is a waste heat stream available, the LAES system can utilise this during the discharge of the system. The effect of injecting this waste heat into the expanding air makes more work available to the generators, thus creating more power from the same amount of Liquid Air. This improves the round trip efficiency considerably, and potentially reduces the CAPEX of the LAES plant by not having to harvest our own waste heat from compression during the re-charge of the system.

I've got serious doubts. Hasn't the problem with the compressed-gas storage always been the efficiency loss due to compression heating? This has that turned up to 11.

If it works it works, and I'm happy to have it. But the proof will be in the prices.

The thing is, you're cooling the air to liquefy it. Pressure doesn't* enter into it until a later stage (you heat the liquid air up again in a smaller volume, thereby creating high pressures to use the air as working fluid). Thus, no compression heat, which is indeed a major drawback of CAES systems.

* Of course, pressure is always a factor when dealing with fluids.

That isn't better. It's worse, actually - you have lots of waste heat and cold (at the wrong times), and the efficiency of those processes isn't great. And hell, unless you're using a TEC, all low-to-high heat movement is done via compression and expansion. That's how your AC works, that's how gas liquifaction equipment works.

Cloudgazer has a better point about utilizing waste , but that still leaves me with doubts about large-scale deployment. Waste cold is uncommon (damn you thermodynamics!).

Lithium-ion batteries can also respond to minute frequency changes on the grid almost instantaneously, whereas LAES systems deliver electricity by turbine, so their delivery response time isn't as quick.

Why not put a few kWh of lithium batteries on-site? Maybe about 5% - 10% of total plant capacity? When demand increases, the lithium batteries pick up the load immediately while the liquid air starts moving through the heat exchanger to generate power. Once the plant starts generating power with the liquid air, some of the power can be used to re-charge the lithium batteries. Or, the solar power (assuming it's solar, doesn't make a ton of sense to liquify air with fossil fuel power) that was used to compress the air could top off the batteries also.

This looks to be a useful add-on to a natural gas plant, where you have a ready supply of both 'waste cold' and waste heat. But without a 'free' way to really chill and heat your pressurized air, it doesn't seem to be worthwhile.

Most designs quite properly work on the T_hot end of that expression. Here, they have an opportunity to *use* their liquid air on the T_cold side of the expression *while it is being expanded to gaseous form*.

Yes, there are all of the usual concerns about Carnot efficiency being unattainable in real-world systems. That does not change the point that a liquid-air system such as this can seriously change the Delta T available.

I've got serious doubts. Hasn't the problem with the compressed-gas storage always been the efficiency loss due to compression heating? This has that turned up to 11.

If it works it works, and I'm happy to have it. But the proof will be in the prices.

The thing is, you're cooling the air to liquefy it. Pressure doesn't* enter into it until a later stage (you heat the liquid air up again in a smaller volume, thereby creating high pressures to use the air as working fluid). Thus, no compression heat, which is indeed a major drawback of CAES systems.

* Of course, pressure is always a factor when dealing with fluids.

To those temperatures usually you're compressing, then cooling, then expanding again. The expansion process drops the temperature that can be used to cool some of the compressed gas. However, once the air stars condensing as a liquid it's a more thermodynamically favorable than dealing with compressed gas that doesn't visit a liquid stage. And it's easier to store a low-pressure liquid than a large volume of high pressure gas.

I've got serious doubts. Hasn't the problem with the compressed-gas storage always been the efficiency loss due to compression heating? This has that turned up to 11.

If it works it works, and I'm happy to have it. But the proof will be in the prices.

The advantage here being it's a liquid storage system. You're not ever compressing a gas (which is energy intensive). You're compressing a liquid - which requires less work.

I thought you couldn't really compress liquid that much?

Exactly why it takes less energy to get from low pressure to high. The work done (and hence the energy required) is the force times the distance traveled. So if you consider a liquid in a piston, it doesn't reduce in volume very much from low pressure to high.

Slight side-track. I visited a friend's off-grid cabin recently. She was very proud to show me her "invention." She uses solar panels for generation and rather than battery storage had the idea to use the excess energy to pump water into a tower. The water in the tower would be released and flow through a small hydro-turbine to generate electricity during times of low-solar/night.

She was very proud and has big thoughts in her head about selling the concept. I didn't have the heart to tell her. I did, however, forward a copy of this article to her this morning.

I fear she'll be crushed.

I'm not sure why she'd be crushed. This is a completely different storage technology. What she's got is a small-scale pumped hydro system. If she could develop a turnkey off-the-shelf system there's no reason why it couldn't potentially be economically viable (for a relatively niche market, probably). It's not a new technology but at the scale she's talking I don't think it's a market that's been adequately exploited.

Most designs quite properly work on the T_hot end of that expression. Here, they have an opportunity to *use* their liquid air on the T_cold side of the expression *while it is being expanded to gaseous form*.

Yes, there are all of the usual concerns about Carnot efficiency being unattainable in real-world systems. That does not change the point that a liquid-air system such as this can seriously change the Delta T available.

That's a losing proposition though. Adding a bunch of enthalpy into the tank is going to attempt to increase the pressure (since it's fixed volume). Since it's a low pressure tank that's a problem. Also, it's always thermodynamically favorable to add energy at the highest possible pressure and reject heat at the lowest. By using your reservoir as a cold sink you're going to be adding heat to the lowest pressure possible. That's not going to end well for efficiency.

Slight side-track. I visited a friend's off-grid cabin recently. She was very proud to show me her "invention." She uses solar panels for generation and rather than battery storage had the idea to use the excess energy to pump water into a tower. The water in the tower would be released and flow through a small hydro-turbine to generate electricity during times of low-solar/night.

She was very proud and has big thoughts in her head about selling the concept. I didn't have the heart to tell her. I did, however, forward a copy of this article to her this morning.

I fear she'll be crushed.

I'm not sure why she'd be crushed. This is a completely different storage technology. What she's got is a small-scale pumped hydro system. If she could develop a turnkey off-the-shelf system there's no reason why it couldn't potentially be economically viable (for a relatively niche market, probably). It's not a new technology but at the scale she's talking I don't think it's a market that's been adequately exploited.

It's definitely a different market and requirements than utility scale solutions. It seems inexpensive to build, even handling wide swings in storage [and "overcharge"] easily, compared to a battery system. And if the power usage is highly variable, ie you were only there on weekends, you might be able to undersize your solar panels to save even more money.

Plus that pumped water (depending on source and/or if it's a closed system or not) could also be used to pressurize her water system in the cabin, irrigate a vegetable garden. or make re-filling that wood fired hot tub / bath much faster :-D [another key cabin DYI project]

[Edit: seems knowledgeable people have pointed out limitations to DYI pumped storage, so I'll defer to them and I'll focus on building my hot tub.]

Most designs quite properly work on the T_hot end of that expression. Here, they have an opportunity to *use* their liquid air on the T_cold side of the expression *while it is being expanded to gaseous form*.

Yes, there are all of the usual concerns about Carnot efficiency being unattainable in real-world systems. That does not change the point that a liquid-air system such as this can seriously change the Delta T available.

That's a losing proposition though. Adding a bunch of enthalpy into the tank is going to attempt to increase the pressure (since it's fixed volume). Since it's a low pressure tank that's a problem. Also, it's always thermodynamically favorable to add energy at the highest possible pressure and reject heat at the lowest. By using your reservoir as a cold sink you're going to be adding heat to the lowest pressure possible. That's not going to end well for efficiency.

That's an interesting point. How about simply flowing the liquid air past a heat exchanger during the expansion phase, once it is outside the tank?

Most designs quite properly work on the T_hot end of that expression. Here, they have an opportunity to *use* their liquid air on the T_cold side of the expression *while it is being expanded to gaseous form*.

Yes, there are all of the usual concerns about Carnot efficiency being unattainable in real-world systems. That does not change the point that a liquid-air system such as this can seriously change the Delta T available.

That's a losing proposition though. Adding a bunch of enthalpy into the tank is going to attempt to increase the pressure (since it's fixed volume). Since it's a low pressure tank that's a problem. Also, it's always thermodynamically favorable to add energy at the highest possible pressure and reject heat at the lowest. By using your reservoir as a cold sink you're going to be adding heat to the lowest pressure possible. That's not going to end well for efficiency.

That's an interesting point. How about simply flowing the liquid air past a heat exchanger during the expansion phase, once it is outside the tank?

If you mean after compression, absolutely. The liquid air is very cold. It's not going to be much warmer after being compressed to the working temperature. Just about any waste heat source can be used for the initial heating. But as with any cogen or regen system, the fundamental problem is that the T_hot you can achieve with crappy heat sources isn't very hot. Your biggest bang for the buck would be to use a storage system like this in conjunction with a commercial boiler used for power generation already. You could use the waste heat for the first part of the heating cycle then use the actual boiler temperature for the high temps you actually want for sending to a turbine. The advantage being you're getting the compression for almost free (well, from storage).

Now, it all depends on just how high pressure they run the turbines. The outlet is going to be atmospheric (or close enough) but there's no reason the temperature need to match the outside. If you're starting with a high enough pressure, your T_cold can go all they way down until the air is starting to think about liquefying again. A heat exchanger could capture that "waste cold" for use in liquefying more air for storage later.

Edit: The ability to go to ridiculously high pressures is much easier to consider when using a liquid stream through the compressor (a pump is the better word for a liquid). The work required to compress a gas makes the capex costs of the compressors too high to consider that idea. And it's a no-go for an internal combustion system. The temperature limit of the first row of turbine blades limits how hot you can be post compression since you still need to be able to add some heat from combustion.

So it's got worse round trip efficiency than CAES, will have massively higher operating cost than CAES, but has a slight advantage in footprint and site selection. That doesn't seem like that compelling of an argument given how efficient distribution grids are. Put the CAES system wherever it can be sited and you'll still have very significantly higher efficiency and won't have to maintain a complex cryo system. I mean if we run out of sites for CAES systems sure, it's worth trying but we're so far from that eventuality that I can't see where this is advantageous to be doing now unless you're looking to export it to places like Hawaii where CAES will be hard or impossible to site.

I think you answered your own question. CAES requires very specific conditions to be considered for installation, while this technology can be plonked down more-or-less anywhere. Its not an either-or, it's expanding options for energy managers. It remains to be seen whether it will be economically viable, and competitive with other storage options (and under what conditions).

Seems like a side business of siphoning off valuable cryogenically-separated gases could make this a winning proposition when otherwise it might not be.

What's the cost relative to a similar battery installation? Both seem like they have advantages, and like chipmunkofdoom2 a hybrid solution seems like it could work well here: reduce the production of harmful chemicals (currently; ISTR an Ars article a while back about a greener battery manufacturing method) necessary in battery production, smooth the transition period.

Lithium-ion batteries can also respond to minute frequency changes on the grid almost instantaneously, whereas LAES systems deliver electricity by turbine, so their delivery response time isn't as quick.

Why not put a few kWh of lithium batteries on-site? Maybe about 5% - 10% of total plant capacity? When demand increases, the lithium batteries pick up the load immediately while the liquid air starts moving through the heat exchanger to generate power. Once the plant starts generating power with the liquid air, some of the power can be used to re-charge the lithium batteries. Or, the solar power (assuming it's solar, doesn't make a ton of sense to liquify air with fossil fuel power) that was used to compress the air could top off the batteries also.

Turbines (and generators) also have the advantage of providing a stabilizing/attenuating effect to the grid, so, turbines are not so bad, but obviously the quick response of lithium batteries would be needed to deal with large spikes.

So it's got worse round trip efficiency than CAES, will have massively higher operating cost than CAES, but has a slight advantage in footprint and site selection. That doesn't seem like that compelling of an argument given how efficient distribution grids are. Put the CAES system wherever it can be sited and you'll still have very significantly higher efficiency and won't have to maintain a complex cryo system. I mean if we run out of sites for CAES systems sure, it's worth trying but we're so far from that eventuality that I can't see where this is advantageous to be doing now unless you're looking to export it to places like Hawaii where CAES will be hard or impossible to site.

I think you answered your own question. CAES requires very specific conditions to be considered for installation, while this technology can be plonked down more-or-less anywhere. Its not an either-or, it's expanding options for energy managers. It remains to be seen whether it will be economically viable, and competitive with other storage options (and under what conditions).

Seems like a side business of siphoning off valuable cryogenically-separated gases could make this a winning proposition when otherwise it might not be.

Lithium-ion batteries can also respond to minute frequency changes on the grid almost instantaneously, whereas LAES systems deliver electricity by turbine, so their delivery response time isn't as quick.

Why not put a few kWh of lithium batteries on-site? Maybe about 5% - 10% of total plant capacity? When demand increases, the lithium batteries pick up the load immediately while the liquid air starts moving through the heat exchanger to generate power. Once the plant starts generating power with the liquid air, some of the power can be used to re-charge the lithium batteries. Or, the solar power (assuming it's solar, doesn't make a ton of sense to liquify air with fossil fuel power) that was used to compress the air could top off the batteries also.

Turbines (and generators) also have the advantage of providing a stabilizing/attenuating effect to the grid, so, turbines are not so bad, but obviously the quick response of lithium batteries would be needed to deal with large spikes.

Well, we could consider the effects of the turbines as inertia. Because, that's literally what they are and how the stabilize the grid. However, in any control system, having more inertia is never as good as having more command authority - which is what batteries provide.

Most designs quite properly work on the T_hot end of that expression. Here, they have an opportunity to *use* their liquid air on the T_cold side of the expression *while it is being expanded to gaseous form*.

Yes, there are all of the usual concerns about Carnot efficiency being unattainable in real-world systems. That does not change the point that a liquid-air system such as this can seriously change the Delta T available.

That's a losing proposition though. Adding a bunch of enthalpy into the tank is going to attempt to increase the pressure (since it's fixed volume). Since it's a low pressure tank that's a problem. Also, it's always thermodynamically favorable to add energy at the highest possible pressure and reject heat at the lowest. By using your reservoir as a cold sink you're going to be adding heat to the lowest pressure possible. That's not going to end well for efficiency.

That's an interesting point. How about simply flowing the liquid air past a heat exchanger during the expansion phase, once it is outside the tank?

If you mean after compression, absolutely. The liquid air is very cold. It's not going to be much warmer after being compressed to the working temperature. Just about any waste heat source can be used for the initial heating. But as with any cogen or regen system, the fundamental problem is that the T_hot you can achieve with crappy heat sources isn't very hot. Your biggest bang for the buck would be to use a storage system like this in conjunction with a commercial boiler used for power generation already. You could use the waste heat for the first part of the heating cycle then use the actual boiler temperature for the high temps you actually want for sending to a turbine. The advantage being you're getting the compression for almost free (well, from storage).

Now, it all depends on just how high pressure they run the turbines. The outlet is going to be atmospheric (or close enough) but there's no reason the temperature need to match the outside. If you're starting with a high enough pressure, your T_cold can go all they way down until the air is starting to think about liquefying again. A heat exchanger could capture that "waste cold" for use in liquefying more air for storage later.

Sounds good to me! You are clearly the mechanical engineering expert here. I am simply a geophysicist with experience on the T_hot side from geothermal power systems.

So it's got worse round trip efficiency than CAES, will have massively higher operating cost than CAES, but has a slight advantage in footprint and site selection. That doesn't seem like that compelling of an argument given how efficient distribution grids are. Put the CAES system wherever it can be sited and you'll still have very significantly higher efficiency and won't have to maintain a complex cryo system. I mean if we run out of sites for CAES systems sure, it's worth trying but we're so far from that eventuality that I can't see where this is advantageous to be doing now unless you're looking to export it to places like Hawaii where CAES will be hard or impossible to site.

I think you answered your own question. CAES requires very specific conditions to be considered for installation, while this technology can be plonked down more-or-less anywhere. Its not an either-or, it's expanding options for energy managers. It remains to be seen whether it will be economically viable, and competitive with other storage options (and under what conditions).

Seems like a side business of siphoning off valuable cryogenically-separated gases could make this a winning proposition when otherwise it might not be.

Liquid nitrogen already costs less than milk.

Noble gases don't, and this system could be used to siphon off CO2 for sequestration if provided the right economic subsidies.